Positive photosensitive resin composition and method for forming cured film using the same

ABSTRACT

The present invention provides a positive photosensitive resin composition including: a resin containing a specific acrylic acid-based constituent unit capable of undergoing dissociation of an acid-dissociable group to produce a carboxyl group, and a constituent unit having a functional group capable of reacting with the carboxyl group to form a covalent bond, the resin being alkali-insoluble or sparingly alkali-soluble and becoming alkali-soluble when the acid-dissociable group dissociates; and a compound capable of generating an acid upon irradiation with an actinic ray or radiation. The present invention also provides a method for forming a cured film using the composition. The positive photosensitive composition is excellent in the sensitivity, film residual ratio and storage stability and by the method for forming a cured film using the positive photosensitive resin composition, a cured film excellent in the heat resistance, adhesion, transmittance and the like can be provided.

This is a Continuation Application of U.S. Application Ser. No. 12/663,016 filed Dec. 4, 2009, which is a National Stage Entry of PCT/JP2008/060388 filed Jun. 5, 2008, which claims priority from JP 2007-149217 filed Jun. 5, 2007, JP 2007-249785 filed Sep. 26, 2007, and JP 2008-146385 filed Jun. 4, 2008, the contents of all of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a positive photosensitive resin composition and a method for forming a cured film using the same. More specifically, the present invention relates to a positive photosensitive resin composition suitable for the formation of a flattening film, a protective film or an interlayer insulating film of electronic components such as liquid crystal display device, integrated circuit device, solid-state imaging device and organic EL, and a method for forming a cured film using the same.

BACKGROUND ART

Conventionally, in electronic components such as liquid crystal display device, integrated circuit device, solid-state imaging device and organic EL, a photosensitive resin composition is generally used when forming a flattening film for imparting flatness to a surface of the electronic component, a protective film for preventing deterioration or damage of the electronic component, or an interlayer insulating film for keeping insulation. For example, in the production of a TFT liquid crystal display device, a backplate is fabricated by providing a polarizing plate on a glass substrate, forming a transparent electroconductive circuit layer such as ITO and a thin film transistor (TFT) thereon, and covering these with an interlayer insulating film, while a top plate is fabricated by providing a polarizing plate on a glass substrate, forming, if desired, patterns of a black matrix layer and a color filter layer, and further forming sequentially a transparent electroconductive circuit layer and an interlayer insulating film, and a liquid crystal is sealed in between the backplate and the top plate after disposing these two plates to oppose through a spacer. In this process, the photosensitive resin composition used when forming the interlayer insulating film is required to be excellent in the sensitivity, residual film ratio, heat resistance, adhesion and transparency. Also, excellent aging stability during storage is required of the photosensitive resin composition.

As regards the photosensitive resin composition, for example, Patent Document 1 proposes a photosensitive resin composition containing (A) a resin soluble in an aqueous alkali solution, which is a polymer of (a) an unsaturated carboxylic acid or an unsaturated carboxylic anhydride, (b) an epoxy group-containing radical polymerizable compound and (c) another radical polymerizable compound, and (B) a radiation-sensitive acid-producing compound, and Patent Document 2 proposes a photosensitive resin composition containing an alkali-soluble acrylic polymer binder, a quinonediazide group-containing compound, a crosslinking agent and a photo-acid generator. However, both of these are not enough in terms of sensitivity, residual film ratio of the unexposed area, resolution and aging stability and are not enough for producing a high-quality liquid crystal display device. Patent Document 3 proposes a chemically amplified positive resist composition containing a crosslinking agent, an acid generator and a resin having a protective group capable of being cleaved by the action of an acid, where the resin itself is insoluble or sparingly soluble in an aqueous alkali solution but becomes soluble in an aqueous alkali solution after cleavage of the protective group. However, this is not enough in terms of adhesion or transmittance and is not enough for producing a high-quality liquid crystal display device. Patent Document 4 proposes a radiation-sensitive resin composition containing an acid generator and a resin having an acetal structure and/or a ketal structure and an epoxy group, but this is low in the sensitivity and is not enough.

Patent Document 1: JP-A-5-165214

Patent Document 2: JP-A-10-153854

Patent Document 3: JP-A-2004-4669

Patent Document 4: JP-A-2004-264623

DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve

An object of the present invention is to provide a positive photosensitive resin composition excellent in the sensitivity, residual film ratio and storage stability, and a method for forming a cured film using the same, which are a positive photosensitive resin composition ensuring that when cured, a cured film excellent in the heat resistance, adhesion, transmittance and the like is obtained, and a method for forming a cured film using the same.

Means for Solving the Problems

The present inventors have made intensive studies to attain the above-described object, as a result, the present invention has been accomplished.

The present invention is as follows.

(1) A positive photosensitive resin composition including at least:

(A) a resin containing a constituent unit represented by following formula (1) having an acid-dissociable group, and a constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond,

the resin being alkali-insoluble or sparingly alkali-soluble and becoming alkali-soluble when the acid-dissociable group dissociates; and

(B) a compound capable of generating an acid upon irradiation with an actinic ray or radiation:

wherein R¹ represents a hydrogen atom, a methyl group, a halogen atom or a cyano group;

each of R² and R³ independently represents a hydrogen atom, a linear or branched alkyl group, or a cycloalkyl group, provided that at least one of R² and R³ represents a linear or branched alkyl group or a cycloalkyl group;

R⁴ represents a linear or branched alkyl group that may be substituted, a cycloalkyl group that may be substituted, or an aralkyl group that may be substituted; and

R² or R³ may combine with R⁴ to form a cyclic ether.

(2) The positive photosensitive resin composition as described in (1) above, wherein the component (B) is a compound capable of generating an acid upon irradiation with an actinic ray at a wavelength of 300 nm or more.

(3) The positive photosensitive resin composition as described in (1) above, wherein the component (B) is a compound containing an oxime sulfonate group represented by following formula (2):

wherein R⁵ represents a linear or branched alkyl group that may be substituted, a cycloalkyl group that may be substituted, or an aryl group that may be substituted.

(4) The positive photosensitive resin composition as described in (1) above, wherein the component (B) is a compound represented by following formula (3):

wherein R⁵ is the same as R⁵ in formula (2);

X represents a linear or branched alkyl group, an alkoxy group or a halogen atom;

m represents an integer of 0 to 3; and when m is 2 or 3, each X may be the same as or different from every other X.

(5) The positive photosensitive resin composition as described in any one of (1) to (4) above, which further includes: (C) an adhesion aid.

(6) A method for forming a cured film, including:

a step of coating and drying the positive photosensitive resin composition described in any one of (1) to (5) above on a substrate to form a coating;

a step of exposing to an actinic ray or radiation through a mask;

a step of developing with an alkali developer to form a pattern; and

a step of heat-treating the obtained pattern.

(7) The method for forming a cured film as described in (6) above, which further includes:

a step of exposing the entire surface after the step of developing with an alkali developer to form a pattern but before the step of heat-treating the obtained pattern.

Furthermore, preferred embodiments of the present invention are set forth below.

(8) The positive photosensitive resin composition as described in any one of (1) to (5) above, wherein the component (B) is contained in an amount of 0.1 to 10 parts by mass per 100 parts by mass of the component (A).

(9) The positive photosensitive resin composition as described in any one of (1) to (5) and (8) above, wherein the component (C) is contained in an amount of 0.1 to 20 parts by mass per 100 parts by mass of the component (A).

Advantage of the Invention

According to the present invention, there can be provided a positive photosensitive resist composition excellent in the sensitivity, residual film ratio and storage stability, and a method for forming a cured film using the same, which are a positive photosensitive resin composition ensuring that when cured, a cured film excellent in the heat resistance, adhesion, transmittance and the like is obtained, and a method for forming a cured film using the same.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is described in detail below.

Incidentally, in the present invention, when a group (atomic group) is denoted without specifying whether substituted or unsubstituted, the group includes both a group having no substituent and a group having a substituent. For example, an “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

The positive photosensitive resin composition of the present invention contains a resin containing a constituent unit represented by the following formula (1) having an acid-dissociable group and a constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond, the resin being alkali-insoluble or sparingly alkali-soluble and becoming alkali-soluble when the acid-dissociable group dissociates (sometimes referred to as a “component (A)”), and may contain other resins. The “acid-dissociable group” as used herein indicates a functional group capable of dissociating in the presence of an acid.

In formula (1), R¹ represents a hydrogen atom, a methyl group, a halogen atom or a cyano group,

each of R² and R³ independently represents a hydrogen atom, a linear or branched alkyl group, or a cycloalkyl group, provided that at least one of R² and R³ represents an alkyl group or a cycloalkyl group,

R⁴ represents a linear or branched alkyl group that may be substituted, a cycloalkyl group that may be substituted, or an aralkyl group that may be substituted, and

R² or R³ may combine with R⁴ to form a cyclic ether.

In formula (1), R¹ is preferably a hydrogen atom or a methyl group.

The alkyl group as R² and R³ is preferably a linear or branched alkyl group having a carbon number of 1 to 6.

The cycloalkyl group as R² and R³ is preferably a cycloalkyl group having a carbon number of 3 to 6.

The alkyl group as R⁴ is preferably a linear or branched alkyl group having a carbon number of 1 to 10.

The cycloalkyl group as R⁴ is preferably a cycloalkyl group having a carbon number of 3 to 10.

The aralkyl group as R⁴ is preferably an aralkyl group having a carbon number of 7 to 10.

In the case where R² combines with R⁴ to form a cyclic ether, R¹ and R³ are preferably combined to form an alkylene chain having a carbon number of 2 to 5.

The alkyl group, cycloalkyl group and aralkyl group as R⁴ may have a substituent, and the substituent is, for example, an alkyl group, an alkoxy group or a halogen atom and preferably has a carbon number of 6 or less.

Examples of the radical polymerizable monomer used for forming the constituent unit represented by formula (1) include a 1-alkoxyalkyl acrylate, a 1-alkoxyalkyl methacrylate, a 1-(haloalkoxy)alkyl acrylate, a 1-(haloalkoxy)alkyl methacrylate, a 1-(aralkyloxy)alkyl acrylate, a 1-(aralkyloxy)alkyl methacrylate, a tetrahydropyranyl acrylate and a tetrahydropyranyl methacrylate. Among these, preferred are a 1-alkoxyalkyl acrylate, a 1-alkoxyalkyl methacrylate, a tetrahydropyranyl acrylate and a tetrahydropyranyl methacrylate, and more preferred are a 1-alkoxyalkyl acrylate and a 1-alkoxyalkyl methacrylate.

Specific examples of the radical polymerizable monomer used for forming the constituent unit represented by formula (1) include 1-ethoxyethyl methacrylate, 1-ethoxyethyl acrylate, 1-methoxyethyl methacrylate, 1-methoxyethyl acrylate, 1-n-butoxyethyl methacrylate, 1-n-butoxyethyl acrylate, 1-isobutoxyethyl methacrylate, 1-(2-chloroethoxy)ethyl methacrylate, 1-(2-ethylhexyloxy)ethyl methacrylate, 1-n-propoxyethyl methacrylate, 1-cyclohexyloxyethyl methacrylate, 1-(2-cyclohexylethoxy)ethyl methacrylate and 1-benzyloxyethyl methacrylate. One of these may be use alone, or two or more kinds thereof may be used in combination.

The radical polymerizable monomer used for forming the constituent unit represented by formula (1) may be a commercially available product or may be synthesized by a known method. For example, the monomer can be synthesized by reacting a (meth)acrylic acid with a vinyl ether in the presence of an acid catalyst as shown below.

Here, R¹, R³ and R⁴ correspond to R¹, R³ and R⁴ in formula (1), and R¹³ and R¹⁴ as —CH(R¹³)(R¹⁴) correspond to R² in formula (1).

While a cured film is formed by the process including a step of coating and drying the positive photosensitive resin composition of the present invention on a substrate to form a coating, a step of exposing the coating to an actinic ray or radiation through a mask, a step of developing the coating with an alkali developer to form a pattern, (if desired, a step of exposing the entire surface), and a step of heat-treating the obtained pattern, the acid-dissociable group (—C(R²)(R³)OR⁴) dissociates from the constituent unit represented by formula (1) in the component (A) in the step of entire surface exposure or heat treatment, and a carboxyl group is produced in the side chain of the component (A).

The “functional group capable of reacting with a carboxyl group to form a covalent bond” in the constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond, which is contained in the component (A) of the present invention, means a functional group that reacts with a carboxyl group produced in the side chain of the component (A) by the heat treatment as described above and forms a covalent bond.

The carboxyl group produced in the side chain of the component (A) and the “functional group capable of reacting with a carboxyl group to form a covalent bond” in the component (A) form a covalent bond by the heat treatment to effect crosslinking, whereby a good cured film is formed.

Examples of the functional group capable of reacting with a carboxyl group to form a covalent bond include an epoxy group and an oxetane group, with an epoxy group being preferred.

The constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond is preferably a constituent unit containing an epoxy group as the functional group, which is formed using a radical polymerizable monomer represented by any one of the following formulae (3) to (5). The molecular weight of the radical polymerizable monomer represented by any one of formulae (3) to (5) is preferably from 100 to 500, more preferably from 120 to 200.

In formulae (3) to (5), X represents a divalent organic group, and examples thereof include —O—, —S— and an organic group such as —COO— and —OCH₂COO—.

R⁷ represents a hydrogen atom, a methyl group or a halogen atom and is preferably a hydrogen atom or a methyl group.

Each of R⁸ to R¹⁵ independently represents a hydrogen atom or an alkyl group and is preferably a hydrogen atom or a methyl group.

n is an integer of 1 to 10.

Specific examples of the radical polymerizable monomer used for forming the constituent unit containing an epoxy group as the functional group capable of reacting with a carboxyl group to form a covalent bond include (meth)acrylates such as glycidyl acrylate, glycidyl methacrylate, 3,4-epoxybutyl acrylate, 3,4-epoxybutyl methacrylate, 4,5-epoxypentyl acrylate, 4,5-epoxypentyl methacrylate, 6,7-epoxyheptyl acrylate and 6,7-epoxyheptyl methacrylate; vinylbenzyl glycidyl ethers such as o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, α-methyl-o-vinylbenzyl glycidyl ether, α-methyl-m-vinylbenzyl glycidyl ether and α-methyl-p-vinylbenzyl glycidyl ether; p-vinylphenyl glycidyl ether; 3,4-epoxycyclohexylmethyl acrylate; and 3,4-epoxycyclohexylmethyl methacrylate. Among these, glycidyl acrylate, glycidyl methacrylate, p-vinylphenyl glycidyl ether, 3,4-epoxycyclohexylmethyl acrylate and 3,4-epoxycyclohexylmethyl methacrylate are preferred, and glycidyl acrylate and glycidyl methacrylate are more preferred.

Also, a constituent unit having an oxetane group as the functional group may be formed using a compound where the epoxy group in those specific examples of the compound having an epoxy group as the functional group is replaced by an oxetane group.

The radical polymerizable monomer used for forming the constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond may be a commercially available product or may be synthesized by a known method.

The content of the constituent unit represented by formula (1) is preferably from 10 to 90 mol %, more preferably from 20 to 50 mol %, based on all repeating units constituting the resin.

The content of the constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond is preferably from 5 to 50 mol %, more preferably from 10 to 40 mol %, based on all repeating units constituting the resin.

In the component (A), a constituent unit other than the constituent unit represented by formula (1) and the constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond may be copolymerized, if desired.

The constituent unit other than the constituent unit represented by formula (1) and the constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond includes constituent units derived from styrene, tert-butoxystyrene, methylstyrene, hydroxystyrene, α-methylstyrene, acetoxystyrene, α-methyl-acetoxystyrene, methoxystyrene, ethoxystyrene, chlorostyrene, methyl vinylbenzoate, ethyl vinylbenzoate, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, benzyl acrylate, benzyl methacrylate, isobornyl acrylate, isobornyl methacrylate, glycidyl methacrylate, or acrylonitrile. One of these constituent units may be used alone, or two or more kinds thereof may be used in combination.

The content of this constituent unit is, as the total amount, preferably from 90 mol % or less, more preferably 60 mol % or less.

The molecular weight of the component (A) is, as the weight average molecular weight in terms of polystyrene, preferably from 1,000 to 200,000, more preferably from 2,000 to 50,000.

As for the component (A), a mixture of two or more kinds of resins containing different constituent units may be used, or a mixture of two or more kinds of resins containing the same constituent unit and differing in the composition may be used.

Also, as for the synthesis method of the component A, various methods are known and, for example, a radical polymerizable monomer mixture containing at least a radical polymerizable monomer used for forming the constituent unit represented by formula (1) and a radial polymerizable monomer used for forming the constituent unit having a functional group capable of reacting a carboxyl group to form covalent bond is polymerized in an organic solvent by using a radial polymerization initiator, whereby the resin may be synthesized.

(B) Compound Capable of Generating an Acid Upon Irradiation with an Actinic Ray or Radiation

Examples of the compound capable of generating an acid upon irradiation with an actinic ray or radiation (sometimes referred to as a “component (B)”), which is used in the present invention, include a sulfonium salt, an iodonium salt, a diazomethane compound, an imidosulfonate compound and an oxime sulfonate compound. One of these may be used alone, or two or more kinds thereof may be used in combination.

As for the acid generated, a compound capable of generating an acid having pKa of 3 or less is preferred, and a compound capable of generating a sulfonic acid is more preferred.

The component (B) is preferably a compound that is sensitized with an actinic ray at a wavelength of 300 nm or more to generate an acid, more preferably a compound containing an oxime sulfonate group represented by formula (2):

In formula (2), R⁵ represents a linear or branched alkyl group that may be substituted, a cycloalkyl group that may be substituted, or an aryl group that may be substituted.

R⁵ is preferably a linear or branched alkyl group that may be substituted, or an aryl group that may be substituted.

The alkyl group of R⁵ is preferably a linear or branched alkyl group having a carbon number of 1 to 10, and the cycloalkyl group is preferably a cycloalkyl group having a carbon number of 3 to 10.

The alkyl group and cycloalkyl group of R⁵ may be substituted, for example, by an alkoxy group having a carbon number of 1 to 10 or an alicyclic group (including a crosslinked alicyclic group such as 7,7-dimethyl-2-oxonorbornyl group; preferably, for example, a bicycloalkyl group).

The aryl group of R⁵ is preferably an aryl group having a carbon number of 6 to 11, more preferably a phenyl group or a naphthyl group. The aryl group of R⁵ may be substituted, for example, by an alkyl group having a carbon number of 1 to 5, an alkoxy group or a halogen atom.

The compound containing an oxime sulfonate group represented by formula (2) is more preferably an oxime sulfonate compound represented by the following formula (3):

In formula (3), R⁵ is the same as R⁵ in formula (2),

X represents a linear or branched alkyl group, an alkoxy group or a halogen atom,

m represents an integer of 0 to 3, and when m is 2 or 3, each X may be the same as or different from every other X.

The alkyl group as X is preferably a linear or branched alkyl group having a carbon number of 1 to 4.

The alkoxy group as X is preferably a linear or branched alkoxy group having a carbon number of 1 to 4.

The halogen atom as X is preferably a chlorine atom or a fluorine atom.

m is preferably 0 or 1.

In particular, a compound where in formula (3), m is 1, X is a methyl group and the substitution position of X is the ortho-position, is preferred.

Specific examples of the oxime sulfonate compound include the following compound (i), compound (ii), compound (iii), compound (iv) and compound (v). One of these may be used alone, or two or more kinds thereof may be used in combination. Also, the compound may be used in combination with another kind of the component (B).

Compounds (i) to (v) are available as a commercial product.

(C) Adhesion Aid

The adhesion aid (C) for use in the present invention is a compound for enhancing adhesion of an insulating film to an inorganic material working out to a substrate, for example, a silicon compound such as silicon, silicon oxide and silicon nitride, or a metal such as gold, copper and aluminum. Specific examples thereof include a silane coupling agent and a thiol-based compound.

The silane coupling agent as the adhesion aid for use in the present invention is intended to modify the interface and is not particularly limited, and a known silane coupling agent may be used.

Preferred examples of the silane coupling agent include γ-glycidoxypropyltrialkoxysilane, γ-glycidoxypropylalkyldialkoxysilane, γ-methacryloxypropyltrialkoxysilane, γ-methacryloxypropylalkyldialkoxysilane, γ-chloropropyltrialkoxysilane, γ-mercaptopropyltrialkoxysilane, β-(3,4-epoxycyclohexyl)ethyltrialkoxysilane and vinyltrialkoxysilane.

Among these, γ-glycidoxypropyltrialkoxysilane and methacryloxypropyltrialkoxysilane are more preferred, and glycidoxypropyltrialkoxysilane is still more preferred.

One of these may be used alone, or two or more kinds thereof may be used in combination. These are effective not only for enhancing the adhesion to a substrate but also for adjusting the taper angle with the substrate.

In the positive photosensitive resin composition of the present invention, as for the mixing ratio of the component (A), component (B) and component (C), the ratio of the component (B) is preferably from 0.1 to 10 parts by mass, more preferably from 0.5 to 5 parts by mass, and the ratio of the component (C) is preferably from 0.1 to 20 parts by mass, more preferably from 0.5 to 10 parts by mass, per 100 parts by mass of the component (A).

<Other Components>

In the positive photosensitive resin composition of the present invention, in addition to the component (A), component (B) and component (C), a basic compound, a surfactant, an ultraviolet absorber, a sensitizer, a plasticizer, a thickener, an organic solvent, an organic or inorganic precipitation inhibitor, and the like may be added, if desired.

<Basic Compound>

The basic compound which can be used may be arbitrarily selected from those used in chemically amplified resists. Examples thereof include an aliphatic amine, an aromatic amine, a heterocyclic amine, a quaternary ammonium hydroxide and a quaternary ammonium carboxylate.

Examples of the aliphatic amine include trimethylamine, diethylamine, triethylamine, di-n-propylamine, tri-n-propylamine, di-n-pentylamine, tri-n-pentylamine, diethanolamine, triethanolamine, dicyclohexylamine and dicyclohexylmethylamine.

Examples of the aromatic amine include aniline, benzylamine, N,N-dimethylaniline and diphenylamine.

Examples of the heterocyclic amine include pyridine, 2-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 4-ethylpyridine, 2-phenylpyridine, 4-phenylpyridine, N-methyl-4-phenylpyridine, 4-dimethylaminopyridine, imidazole, benzimidazole, 4-methylimidazole, 2-phenylbenzimidazole, 2,4,5-triphenylimidazole, nicotine, nicotinic acid, nicotinamide, quinoline, 8-oxyquinoline, pyrazine, pyrazole, pyridazine, purine, pyrrolidine, piperidine, piperazine, morpholine, 4-methylmorpholine, 1,5-diazabicyclo[4,3,0]-5-nonene and 1,8-diazabicyclo[5,3,0]-7-undecene.

Examples of the quaternary ammonium hydroxide include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide and tetra-n-hexylammonium hydroxide.

Examples of the quaternary ammonium carboxylate include tetramethylammonium acetate, tetramethylammonium benzoate, tetra-n-butylammonium acetate and tetra-n-butylammonium benzoate.

The amount of the basic compound blended is preferably from 0.001 to 1 part by mass, more preferably from 0.005 to 0.2 parts by mass, per 100 parts by mass of the component (A).

<Surfactant>

As for the surfactant, any of an anionic surfactant, a cationic surfactant, a nonionic surfactant and an amphoteric surfactant may be used, but the preferred surfactant is a nonionic surfactant. Examples of the nonionic surfactant which can be used include polyoxyethylene higher alkyl ethers, polyoxyethylene higher alkyl phenyl ethers, higher fatty acid diesters of polyoxyethylene glycol, and silicon-containing or fluorine-containing surfactants. Also, the nonionic surfactant includes respective series of, as trade names, KP (produced by Shin-Etsu Chemical Co., Ltd.), Polyflow (produced by Kyoeisha Chemical Co., Ltd.), EFtop (produced by JEMCO), Megaface (produced by Dainippon Ink and Chemicals, Inc.), Florad (produced by Sumitomo 3M, Ltd.), Asahi Guard, Surflon (produced by Asahi Glass Co., Ltd.) and PolyFox (produced by OMNOVA).

One surfactant may be used alone, or two or more kinds of surfactants may be used in combination.

The amount of the surfactant blended is preferably 10 parts by mass or less, more preferably from 0.01 to 10 parts by mass, still more preferably from 0.05 to 2 parts by mass, per 100 parts by mass of the component (A).

<Plasticizer>

Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, didodecyl phthalate, polyethylene glycol, glycerin, dimethyl glycerin phthalate, dibutyl tartrate, dioctyl adipate and triacetyl glycerin.

The amount of the plasticizer blended is preferably from 0.1 to 30 parts by mass, more preferably from 1 to 10 parts by mass, per 100 parts by mass of the component (A).

<Solvent>

The positive photosensitive resin composition of the present invention is used as a solution by dissolving the above-described components in a solvent. Examples of the solvent used for the positive photosensitive resin composition of the present invention include:

(a) ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether and ethylene glycol monobutyl ether;

(b) ethylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether and ethylene glycol dipropyl ether;

(c) ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate and ethylene glycol monobutyl ether acetate;

(d) propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether and propylene glycol monobutyl ether;

(e) propylene glycol dialkyl ethers such as propylene glycol dimethyl ether and propylene glycol diethyl ether;

(f) propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate and propylene glycol monobutyl ether acetate;

(g) diethylene glycol monoalkyl ethers such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether;

(h) diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether and diethylene glycol ethyl methyl ether;

(i) diethylene glycol monoalkyl ether acetates such as diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether acetate and diethylene glycol monobutyl ether acetate;

(j) dipropylene glycol monoalkyl ethers such as dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether and dipropylene glycol monobutyl ether;

(k) dipropylene glycol dialkyl ethers such as dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether and dipropylene glycol ethyl methyl ether;

(l) dipropylene glycol monoalkyl ether acetates such as dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monopropyl ether acetate and dipropylene glycol monobutyl ether acetate;

(m) lactic acid esters such as methyl lactate, ethyl lactate, n-propyl lactate, isopropyl lactate, n-butyl lactate, isobutyl lactate, n-amyl lactate and isoamyl lactate;

(n) aliphatic carboxylic acid esters such as n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, n-hexyl acetate, 2-ethylhexyl acetate, ethyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate, methyl butyrate, ethyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate and isobutyl butyrate;

(o) other esters such as ethyl hydroxyacetate, ethyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, methyl acetoacetate, ethyl acetoacetate, methyl pyruvate and ethyl pyruvate;

(p) ketones such as methyl ethyl ketone, methyl propyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, 2-heptanone, 3-heptanone, 4-heptanone and cyclohexanone;

(q) amides such as N-methylformamide, N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide and N-methylpyrrolidone; and

(r) lactones such as γ-butyrolactone.

Also, a solvent such as benzyl ethyl ether, dihexyl ether, ethylene glycol monophenyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, isophorone, caproic acid, caprylic acid, 1-octanol, 1-nonal, benzyl alcohol, anisole, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, ethylene carbonate and propylene carbonate may be further added, if desired, to the solvent above.

One solvent may be used alone, or two or more kinds of solvents may be used in combination.

The amount of the solvent blended is preferably from 50 to 3,000 parts by mass, more preferably from 100 to 2,000 parts by mass, still more preferably from 100 to 500 parts by mass, per 100 parts by mass of the component (A).

By virtue of using the positive photosensitive resin composition containing the components (A) and (B), a positive photosensitive resin composition excellent in the sensitivity, residual film ratio and aging stability can be provided, which is a positive photosensitive resin composition ensuring that when cured, a cured film excellent in the heat resistance, adhesion, transparency and the like is obtained.

<Method for Forming Cured Film>

The method for forming a cured film using the positive photosensitive resin composition of the present invention is described below.

The positive photosensitive resin composition of the present invention is coated on a substrate and dried by heating to form a coating on the substrate.

The obtained coating is irradiated with an actinic ray or radiation, whereby the component (B) decomposes and an acid is generated. By the catalytic action of the acid generated, the acid-dissociable group in the constituent unit represented by formula (1) contained in the component (A) dissociates through a hydrolysis reaction, and a carboxyl group is produced. The reaction formula of this hydrolysis reaction is shown below.

In order to accelerate the hydrolysis reaction, post exposure baking: Post Exposure Bake (hereinafter sometimes referred to as “PEB”) may be performed, if desired. Here, if the heating temperature is high, the carboxyl group generated causes a crosslinking reaction with the constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond, and it becomes impossible to effect development.

Actually, when tert-butyl methacrylate is used in place of the repeating unit represented by formula (1), the activation energy of acid dissociation reaction is high and PEB must be performed at a high temperature to dissociate the acid-dissociable group, but a crosslinking reaction occurs at the same time and an image cannot be obtained.

On the other hand, the acid-dissociable group represented by formula (1) of the present invention is low in the activation energy of acid decomposition and produces a carboxyl group by readily decomposing in the presence of an acid derived from an acid generator upon exposure, so that PEB need not be performed and a positive image can be formed by development.

Incidentally, decomposition of the acid-dissociable group may be accelerated by performing PEB at a relatively low temperature without causing a crosslinking reaction.

The PEB temperature is preferably 130° C. or less, more preferably 110° C. or less, still more preferably 80° C. or less.

The obtained positive image is then heated, as a result, the acid-dissociable group in formula (1) thermally decomposes to produce a carboxyl group, and the carboxyl group is crosslinked with a structure to be crosslinked, whereby a cured film can be formed. This heating is preferably performed at a high temperature of 150° C. or more, more preferably at 180 to 250° C., still more preferably at 200 to 250° C.

The heating time may be appropriately set according to the heating temperature and the like but is preferably from 10 to 90 minutes.

When a step of irradiating the entire surface with an actinic ray or radiation is added before the heating step, the crosslinking reaction can be accelerated by an acid generated upon irradiation with an actinic ray or radiation.

The method of forming a cured film using the positive photosensitive resin composition of the present invention is specifically described below.

Preparation Method of Composition Solution:

The components (A) and (B) and other components to be blended are mixed in a predetermined ratio by an arbitrary method and dissolved with stirring to prepare a composition solution. For example, the composition solution may also be prepared by previously dissolving each component in a solvent to obtain a solution and mixing these solutions in a predetermined ratio. The composition solution prepared in this way may be filtered using a filter or the like having a pore size of 0.2 μM and then used.

<Formation Method of Coating>

The composition solution is coated on a predetermined substrate, and the solvent is removed by heating (hereinafter referred to as “pre-baking”), whereby a desired coating can be formed. For example, in the production of a liquid crystal display device, examples of the substrate include a glass plate having provided thereon a polarizing plate, where a black matrix layer and a color filter layer are further provided, if desired, and a transparent electroconductive circuit layer is further provided thereon. The coating method on the substrate is not particularly limited and, for example, a method such as spraying method, roll coating method and rotary coating method may be used.

Also, the heating conditions at the pre-baking must be set such that in the unexposed area, an acid-dissociable group in the repeating unit represented by formula (1) in the component (A) dissociates and the component (A) thereby becomes insoluble in an alkali developer, and although the conditions vary depending on the kind and blending ratio of each component, the heating is preferably performed approximately at 80 to 130° C. for 30 to 120 seconds.

<Pattern Forming Method>

The substrate having provided thereon the coating is irradiated with an actinic ray or radiation through a mask having a predetermined pattern and after performing, if desired, a heat treatment (PEB), the exposed area is removed using a developer to form an image pattern.

For the irradiation of an actinic ray or radiation, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a chemical lamp, an excimer laser generator or the like may be used, but an actinic ray at a wavelength of 300 nm or more, such as g-line, i-line and h-line, is preferred. Also, if desired, the irradiation light may be adjusted through a spectral filter such as long wavelength cut filter, short wavelength cut filter and band pass filter.

Examples of the developer which can be used include aqueous solutions of: alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal bicarbonates such as sodium bicarbonate and potassium bicarbonate; ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and choline hydroxide; sodium silicate; and sodium metasilicate. Also, an aqueous solution obtained by adding a water-soluble organic solvent such as methanol or ethanol and a surfactant in appropriate amounts to the above-described aqueous solution of alkalis may be used as the developer.

The pH of the developer is preferably from 10.0 to 14.0.

The development time is preferably from 30 to 180 seconds, and the development method may be any of puddling, dipping and the like. After the development, washing with running water is preferably performed for 30 to 90 seconds, whereby a desired pattern can be formed.

<Crosslinking Step>

The pattern having an unexposed area obtained by development is heat-treated using a heating device such as hot plate or oven at a predetermined temperature, for example, at 180 to 250° C., for a predetermined time, for example, for 5 to 30 minutes on a hot plate or for 30 to 90 minutes in an oven, as a result, the acid-dissociable group in the component (A) dissociates to generate a carboxyl group and the carboxyl group is allowed to react and crosslink with a structure to be crosslinked, whereby a protective film or interlayer insulating film excellent in the heat resistance, hardness and the like can be formed. Furthermore, the transparency can also be enhanced by performing the heat treatment in a nitrogen atmosphere.

Incidentally, in advance of the heat treatment, the substrate after pattern formation is preferably irradiated with an actinic ray or radiation to generate an acid from the component (B) present in the unexposed portion.

EXAMPLES

The present invention is described in greater detail below by referring to Examples, but the present invention is not limited to these Examples.

Synthesis Example 1 Synthesis of A-1

Into a 500 ml-volume three-neck flask, 67.1 g (0.36 mol) of 1-n-butoxyethyl methacrylate, 34.1 g (0.24 mol) of glycidyl methacrylate and 300 ml of methyl isobutyl ketone were charged. A catalytic amount of 2,2′-azobis(methyl 2-methyipropionate) was added thereto as a radical polymerization initiator, and polymerization was allowed to proceed at 80° C. for 6 hours in a nitrogen stream. The reaction solution was cooled and then poured in a large amount of heptane to precipitate a polymer. The crystal was collected by filtration and dissolved in propylene glycol monomethyl ether acetate, and heptane and methyl isobutyl ketone contained in the solution were removed by distillation under reduced pressure to obtain Polymer A-1 (1-n-butoxyethyl methacrylate/glycidyl methacrylate) as a propylene glycol monomethyl ether acetate solution.

In the obtained polymer, the constituent molar ratio between 1-n-butoxyethyl methacrylate unit and glycidyl methacrylate unit was found to be about 60:40 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 8,000 and the molecular weight distribution (Mw/Mn) was 1.8.

Synthesis Example 2 Synthesis of A-2

Into a 500 ml-volume three-neck flask, 47.5 g (0.3 mol) of 1-ethoxyethyl methacrylate, 25.6 g (0.18 mol) of glycidyl methacrylate, 21.2 g (0.12 mol) of benzyl methacrylate and 300 ml of methyl isobutyl ketone were charged. A catalytic amount of 2,2′-azobis(methyl 2-methylpropionate) was added thereto as a radical polymerization initiator, and polymerization was allowed to proceed at 80° C. for 6 hours in a nitrogen stream. The reaction solution was cooled and then poured in a large amount of heptane to precipitate a polymer. The crystal was collected by filtration and dissolved in diethylene glycol dimethyl ether, and heptane and methyl isobutyl ketone contained in the solution were removed by distillation under reduced pressure to obtain Polymer A-2 (1-ethoxyethyl methacrylate/glycidyl methacrylate/benzyl methacrylate) as a diethylene glycol dimethyl ether solution.

In the obtained polymer, the constituent molar ratio of 1-ethoxyethyl methacrylate unit, glycidyl methacrylate unit and benzyl methacrylate unit was found to be about 50:30:20 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 7,000 and the molecular weight distribution (Mw/Mn) was 1.7.

Synthesis Example 3 Synthesis of A-3

Into a 500 ml-volume three-neck flask, 79.3 g (0.36 mol) of 1-benzyloxyethyl methacrylate, 23.1 g (0.18 mol) of glycidyl acrylate, 7.8 g (0.06 mol) of 2-hydroxyethyl methacrylate and 300 ml of methyl isobutyl ketone were charged. A catalytic amount of 2,2′-azobis(methyl 2-methylpropionate) was added thereto as a radical polymerization initiator, and polymerization was allowed to proceed at 80° C. for 6 hours in a nitrogen stream. The reaction solution was cooled and then poured in a large amount of heptane to precipitate a polymer. The crystal was collected by filtration and dissolved in diethylene glycol ethyl methyl ether, and heptane and methyl isobutyl ketone contained in the solution were removed by distillation under reduced pressure to obtain Polymer A-3 (1-benzyloxyethyl methacrylate/glycidyl acrylate/2-hydroxyethyl methacrylate) as a diethylene glycol ethyl methyl ether solution.

In the obtained polymer, the constituent ratio of 1-benzyloxyethyl methacrylate unit, glycidyl acrylate unit and 2-hydroxyethyl methacrylate unit was found to be about 60:30:10 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 10,000 and the molecular weight distribution (Mw/Mn) was 1.8.

Synthesis Example 4 Synthesis of A-4

Into a 500 ml-volume three-neck flask, 43.3 g (0.3 mol) of 1-ethoxyethyl acrylate, 25.6 g (0.18 mol) of glycidyl methacrylate, 21.2 g (0.12 mol) of benzyl methacrylate and 300 ml of methyl isobutyl ketone were charged. A catalytic amount of 2,2′-azobis(methyl 2-methylpropionate) was added thereto as a radical polymerization initiator, and polymerization was allowed to proceed at 80° C. for 6 hours in a nitrogen stream. The reaction solution was cooled and then poured in a large amount of heptane to precipitate a polymer. The crystal was collected by filtration and dissolved in propylene glycol monomethyl ether acetate, and heptane and methyl isobutyl ketone contained in the solution were removed by distillation under reduced pressure to obtain Polymer A-4 (1-ethoxyethyl acrylate/glycidyl methacrylate/benzyl methacrylate) as a propylene glycol monomethyl ether acetate solution.

In the obtained polymer, the constituent ratio of 1-ethoxyethyl acrylate unit, glycidyl methacrylate unit and benzyl methacrylate unit was found to be about 50:30:20 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 8,000 and the molecular weight distribution (Mw/Mn) was 1.7.

Synthesis Example 5 Synthesis of A-5

Into a 500 ml-volume three-neck flask, 76.4 g (0.36 mol) of 1-cyclohexyloxyethyl methacrylate, 35.3 g (0.18 mol) of 3,4-epoxycyclohexylmethyl methacrylate (Cyclomer M100, produced by Daicel Chemical Industries, Ltd.), 7.8 g (0.06 mol) of 2-hydroxyethyl methacrylate and 300 ml of methyl isobutyl ketone were charged. A catalytic amount of 2,2′-azobis(methyl 2-methylpropionate) was added thereto as a radical polymerization initiator, and polymerization was allowed to proceed at 80° C. for 6 hours in a nitrogen stream. The reaction solution was cooled and then poured in a large amount of heptane to precipitate a polymer. The crystal was collected by filtration and dissolved in diethylene glycol dimethyl ether, and heptane and methyl isobutyl ketone contained in the solution were removed by distillation under reduced pressure to obtain Polymer A-5 (1-cyclohexyloxyethyl methacrylate/3,4-epoxycyclohexylmethyl methacrylate/2-hydroxyethyl methacrylate) as a diethylene glycol dimethyl ether solution.

In the obtained polymer, the constituent ratio of 1-cyclohexyloxyethyl methacrylate unit, 3,4-epoxycyclohexylmethyl methacrylate unit and 2-hydroxyethyl methacrylate unit was found to be about 60:30:10 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 6,000 and the molecular weight distribution (Mw/Mn) was 1.8.

Synthesis Example 6 Synthesis of A-6

Into a 500 ml-volume three-neck flask, 57.0 g (0.36 mol) of 2-tetrahydropyranyl methacrylate, 31.7 g (0.18 mol) of p-vinylphenyl glycidyl ether, 7.8 g (0.06 mol) of 2-hydroxyethyl methacrylate and 300 ml of methyl isobutyl ketone were charged. A catalytic amount of 2,2′-azobis(methyl 2-methylpropionate) was added thereto as a radical polymerization initiator, and polymerization was allowed to proceed at 80° C. for 6 hours in a nitrogen stream. The reaction solution was cooled and then poured in a large amount of heptane to precipitate a polymer. The crystal was collected by filtration and dissolved in diethylene glycol ethyl methyl ether, and heptane and methyl isobutyl ketone contained in the solution were removed by distillation under reduced pressure to obtain Polymer A-6 (2-tetrahydropyranyl methacrylate/p-vinylphenyl glycidyl ether/2-hydroxyethyl methacrylate) as a diethylene glycol ethyl methyl ether solution.

In the obtained polymer, the constituent ratio of 2-tetrahydropyranyl methacrylate unit, p-vinylphenyl glycidyl ether unit and 2-hydroxyethyl methacrylate unit was found to be about 60:30:10 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 7,000 and the molecular weight distribution (Mw/Mn) was 1.8.

Synthesis Example 7 Synthesis of A-7

Into a 500 ml-volume three-neck flask, 38.0 g (0.24 mol) of 1-ethoxyethyl methacrylate, 21.3 g (0.15 mol) of glycidyl methacrylate, 26.4 g (0.15 mol) of benzyl methacrylate, 5.2 g (0.06 mol) of methacrylic acid and 300 ml of methyl isobutyl ketone were charged. A catalytic amount of 2,2′-azobis(methyl 2-methylpropionate) was added thereto as a radical polymerization initiator, and polymerization was allowed to proceed at 80° C. for 6 hours in a nitrogen stream. The reaction solution was cooled and then poured in a large amount of heptane to precipitate a polymer. The crystal was collected by filtration and dissolved in a mixed solvent of propylene glycol monomethyl ether acetate and diethylene glycol ethyl methyl ether, and heptane and methyl isobutyl ketone contained in the solution were removed by distillation under reduced pressure to obtain Polymer A-7 (1-ethoxyethyl methacrylate/glycidyl methacrylate/benzyl methacrylate/methacrylic acid) as a solution in a mixed solvent of propylene glycol monomethyl ether acetate and diethylene glycol ethyl methyl ether.

In the obtained polymer, the constituent ratio of 1-ethoxyethyl methacrylate unit, glycidyl methacrylate unit, benzyl methacrylate unit and methacrylic acid was found to be about 40:25:25:10 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 7,000 and the molecular weight distribution (Mw/Mn) was 1.7.

Synthesis Example 8 Synthesis of A-8

Into a 500 ml-volume three-neck flask, 47.5 g (0.3 mol) of 1-ethoxyethyl methacrylate, 33.2 g (0.18 mol) of (1-ethyl-3-oxacyclobutyl)methyl methacrylate, 21.2 g (0.12 mol) of benzyl methacrylate and 300 ml of methyl isobutyl ketone were charged. A catalytic amount of 2,2′-azobis(methyl 2-methylpropionate) was added thereto as a radical polymerization initiator, and polymerization was allowed to proceed at 80° C. for 6 hours in a nitrogen stream. The reaction solution was cooled and then poured in a large amount of heptane to precipitate a polymer. The crystal was collected by filtration and dissolved in diethylene glycol dimethyl ether, and heptane and methyl isobutyl ketone contained in the solution were removed by distillation under reduced pressure to obtain Polymer A-8 (1-ethoxyethyl methacrylate/(1-ethyl-3-oxacyclobutyl)methyl methacrylate/benzyl methacrylate) as a diethylene glycol dimethyl ether solution.

In the obtained polymer, the constituent ratio of 1-ethoxyethyl methacrylate unit, (1-ethyl-3-oxacyclobutyl)methyl methacrylate unit and benzyl methacrylate unit was found to be about 50:30:20 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 8,000 and the molecular weight distribution (Mw/Mn) was 1.7.

Comparative Synthesis Example 1 Synthesis of A′-9

Into a 500 ml-volume three-neck flask, 42.7 g (0.3 mol) of tert-butyl methacrylate, 21.3 g (0.15 mol) of glycidyl methacrylate, 26.4 g (0.15 mol) of benzyl methacrylate and 300 ml of methyl isobutyl ketone were charged. A catalytic amount of 2,2′-azobis(methyl 2-methylpropionate) was added thereto as a radical polymerization initiator, and polymerization was allowed to proceed at 80° C. for 6 hours in a nitrogen stream. The reaction solution was cooled and then poured in a large amount of heptane to precipitate a polymer. The crystal was collected by filtration and dissolved in propylene glycol monomethyl ether acetate, and heptane and methyl isobutyl ketone contained in the solution were removed by distillation under reduced pressure to obtain Polymer A′-9 (tert-butyl methacrylate/glycidyl methacrylate/benzyl methacrylate) as a propylene glycol monomethyl ether acetate solution.

In the obtained polymer, the constituent ratio of tert-butyl methacrylate unit, glycidyl methacrylate unit and benzyl methacrylate unit was found to be about 50:25:25 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 7,000 and the molecular weight distribution (Mw/Mn) was 1.7.

Comparative Synthesis Example 2 Synthesis of N-10

Into a 500 ml-volume three-neck flask, 66.4 g (0.42 mol) of 1-ethoxyethyl methacrylate, 31.7 g (0.18 mol) of benzyl methacrylate and 300 ml of methyl isobutyl ketone were charged. A catalytic amount of 2,2′-azobis(methyl 2-methylpropionate) was added thereto as a radical polymerization initiator, and polymerization was allowed to proceed at 80° C. for 6 hours in a nitrogen stream. The reaction solution was cooled and then poured in a large amount of heptane to precipitate a polymer. The crystal was collected by filtration and dissolved in propylene glycol monomethyl ether acetate, and heptane and methyl isobutyl ketone contained in the solution were removed by distillation under reduced pressure to obtain Polymer A′-10 (1-ethoxyethyl methacrylate/benzyl methacrylate) as a propylene glycol monomethyl ether acetate solution.

In the obtained polymer, the constituent ratio of 1-ethoxyethyl methacrylate unit and benzyl methacrylate unit was found to be about 70:30 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 7,000 and the molecular weight distribution (Mw/Mn) was 1.7.

Comparative Synthesis Example 3 Synthesis of A′-11

Into a 500 ml-volume three-neck flask, 72.1 g of poly-4-hydroxystyrene (VP-8000, produced by Nippon Soda Co., Ltd.), 16.4 g of ethyl vinyl ether and 300 ml of ethyl acetate were charged. A catalytic amount of para-toluenesulfonic acid was added, and reaction was allowed to proceed at room temperature for 3 hours in a nitrogen stream. After adding a small amount of triethylamine, the solution was washed with pure water. Propylene glycol monomethyl ether acetate was added to the ethyl acetate layer, and ethyl acetate was removed by distillation under reduced pressure to obtain Polymer A′-11 (p-1-ethoxyethoxystyrene/p-hydroxystyrene) as a propylene glycol monomethyl ether acetate solution.

In the obtained polymer, the constituent ratio of p-1-ethoxyethoxystyrene unit and p-hydroxystyrene unit was found to be about 35:65 from NMR measurement. Also, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 9,000 and the molecular weight distribution (Mw/Mn) was 1.2.

Comparative Synthesis Example 4 Synthesis of A′-12

Synthesis of A′-12 was performed in accordance with Synthesis Example 1 of JP-A-2004-264623.

Into a three-neck flask, 7 parts by mass of 2,2′-azobis(2,4-dimethylvaleronitrile) and 200 parts by mass of diethylene glycol ethyl methyl ether were charged and subsequently, 40 parts by mass of 1-(cyclohexyloxy)ethyl methacrylate, 5 parts by mass of styrene, 45 parts by mass of glycidyl methacrylate, 10 parts by mass of 2-hydroxyethyl methacrylate and 3 parts by mass of α-methylstyrene dimer were charged. After nitrogen substitution, stirring was gently started. The temperature of the solution was raised to 70° C., and this temperature was kept for 5 hours to obtain a polymer solution containing a copolymer (A′-12). As for the molecular weight of the obtained polymer, GPC measurement using polystyrene as the standard revealed that the weight average molecular weight was about 11,000 and the molecular weight distribution (Mw/Mn) was 1.9.

Examples 1 to 10 and Comparative Examples 1 to 5 (1) Preparation of Positive Photosensitive Resin Composition Solution

A uniform solution was obtained by mixing the components shown in Table 1 below and then filtered using a polytetrafluoroethylene-made filter of 0.2 μm to prepare a positive photosensitive resin composition solution.

(2) Evaluation of Storage Stability

The viscosity at 23° C. of the positive photosensitive resin composition solution was measured using an E-type viscometer manufactured by Toki Sangyo Co., Ltd. Also, the viscosity of the composition after storage in a constant temperature bath at 23° C. for one month was measured. The storage stability was rated A when the increase of viscosity after storage at room temperature for one month based on the viscosity after the preparation was less than 5%, and rated B when 5% or more. The results are shown in Table 2 below.

(3) Evaluation of Sensitivity and Residual Film Ratio at Development

The positive photosensitive resin composition solution was spin-coated on a silicon wafer having thereon a silicon oxide film and then pre-baked on a hot plate at 100° C. for 60 seconds to form a coating of 3 μm in thickness.

The coating was then exposed through a predetermined mask by using an i-line stepper (FPA-3000i5+, manufactured by Canon Inc.), baked at 50° C. for 60 seconds, developed with an alkali developer shown in Table 2 (an aqueous 2.38 mass % or 0.4 mass % tetramethylammonium hydroxide solution) at 23° C. for 60 seconds and then rinsed with ultrapure water for 1 minute. The optimal exposure dose (Eopt) when resolving a 5-μm line-and-space at 1:1 by these operations was taken as the sensitivity.

The film thickness of the unexposed area after development was measured and by determining the ratio to the film thickness after coating (film thickness of unexposed area after development÷film thickness after coating×100(%)), the residual film ratio at the development was evaluated.

The evaluation results of sensitivity and residual film ratio at development are shown in Table 2.

(4) Evaluation of Heat Resistance, Transmittance and Adhesion

A coating was formed in the same manner as in (3) above except that in (3) above, a transparent substrate (Corning 1737, produced by Corning Inc.) was used in place of the silicon wafer having thereon a silicon oxide film. The coating was exposed to an ultraviolet ray at 365 nm with a light intensity of 18 mW/cm² by using a proximity exposure device (UX-1000SM, manufactured by Ushio Inc.) while tightly contacting a predetermined mask with the coating, then developed with an alkali developer shown in Table 2 (an aqueous 2.38 mass % or 0.4 mass % tetramethylammonium hydroxide solution) at 23° C. for 60 seconds, and rinsed with ultrapure water for 1 minute. By these operations, a pattern where a 10-μm line-and-space became 1:1 was formed. The obtained pattern was further subjected to entire surface exposure for 100 seconds and then heated in an oven at 220° C. for 1 hour to form a heat-cured film on the glass substrate.

The evaluation of heat resistance was performed by measuring the rate of change in the bottom dimension between before and after heat curing (1−bottom dimension of heat-cured film÷bottom dimension after development)×100(%). The heat resistance was rated A when the rate of change was less than 5%, and rated C when 5% or more.

The transmittance of the unexposed area (a portion that was the unexposed area when the coating was exposed through a mask) of the heat-cured film obtained was measured by a spectrophotometer (U-3000, manufactured by Hitachi, Ltd.) in the wavelength range of 400 to 800 nm. The transmittance was rated A when the minimum transmittance exceeded 95%, rated B when from 90 to 95%, and rated C when less than 90%.

The heat-cured film was incised vertically and horizontally by a cutter at intervals of 1 mm, and a tape peeling test was performed using Scotch Tape. The adhesion between the cured film and the substrate was evaluated from the area of the cured film transferred to the back surface of the tape. The adhesion was rated A when the area was less than 1%, rated B when from 1 to less than 5%, and rated C when 5% or more.

The evaluation results of heat resistance, transmittance and adhesion are shown in Table 2.

TABLE 1 Basic Component (A) Component (B) Component (C) Compound Solvent Surfactant parts by parts by parts by parts by parts by parts by kind mass kind mass kind mass kind mass kind mass kind mass Example 1 A-1 100 B1 2.5 C1 2.1 D1 0.02 E1 160 F1 0.05 Example 2 A-2 100 B2 3.6 C2 2.1 D2 0.02 E2 160 F1 0.05 Example 3 A-3 100 B3 3.0 C1 2.1 D1 0.02 E3 160 F2 0.05 Example 4 A-4 100 B4 3.3 C1 2.1 D2 0.02 E1 160 F2 0.05 Example 5 A-5 100 B1 + B4 B1:1.6 + B4:1.6 C1 2.1 D1 0.02 E2 160 F3 0.05 Example 6 A-6 100 B1 3.0 C3 2.1 D1 0.02 E3 160 F3 0.05 Example 7 A-7 100 B1 2.5 C1 2.1 D1 0.02 E1 + E3 E1:80 + E3:80 F1 0.05 Example 8 A-8 100 B1 3.0 C1 2.1 D1 0.02 E3 160 F1 0.05 Example 9 A-1 100 B1 2.5 — — D1 0.02 E1 160 F1 0.05 Example 10 A-1 100 B5 3.5 C1 2.1 D1 0.02 E1 160 F1 0.05 Comparative A′-9 100 B1 3.6 C1 2.1 D1 0.02 E1 160 F1 0.05 Example 1 Comparative A′-10 100 B1 3.6 C1 2.1 D1 0.02 E1 160 F1 0.05 Example 2 Comparative A′-11 100 B1 3.0 C1 2.1 D1 0.02 E1 160 F1 0.05 Example 3 Comparative A′-12 100 B′6 10 — — — — E3 257 — — Example 4 Comparative A′-12 100 B′6 5 — — — — E3 245 — — Example 5

The components (A), (B) and (C), the basic compound and the solvent shown in Table 1 are as follows.

Component (A):

The numerical value on the right side of the constituent unit indicates the molar ratio of the constituent unit.

Component (B):

Component (C):

-   C1: γ-glycidoxypropyltrimethoxysilane -   C2: β-(3,4-epoxycyclohexy)ethyltrimethoxysilane -   C3: γ-methacryloxypropyltrimethoxysilane     [Basic Compound] -   D1: 4-dimethylaminopyridine -   D2: 1,5-diazabicyclo[4,3,0]-5-nonene     [Solvent] -   E1: propylene glycol monomethyl ether acetate -   E2: diethylene glycol dimethyl ether -   E3: diethylene glycol ethyl methyl ether     [Surfactant] -   F1: Florad F-430 (produced by Sumitomo 3M, Ltd.) -   F2: Megaface R08 (produced by Dainippon Ink and Chemicals, Inc.) -   F3: PolyFox PF-6320 (produced by OMNOVA)

TABLE 2 Residual Concentration of Storage Sensitivity (Eopt) Film Heat Developer (mass %) Stability (mJ/cm²) Ratio (%) Resistance Adhesion Transmittance Example 1 2.38 A 52 98 A A A Example 2 2.38 A 55 97 A A A Example 3 2.38 A 53 98 A A A Example 4 2.38 A 56 97 A A A Example 5 2.38 A 57 98 A A A Example 6 2.38 A 52 97 A A A Example 7 2.38 A 58 97 A A A Example 8 2.38 A 56 97 B A A Example 9 2.38 A 53 98 A B A Example 10 0.4 A 58 99 A A A Comparative 2.38 A Image was not formed. A A Example 1 Comparative 2.38 A 53 98 C A A Example 2 Comparative 2.38 A 51 97 C A B Example 3 Comparative 2.38 A >800 99 A C A Example 4 Comparative 0.4 A >800 99 A C A Example 5

As apparent from Table 2, the positive photosensitive resin composition of the present invention is excellent in the sensitivity, residual film ratio and storage stability and when cured, can form a cured film excellent in the heat resistance, adhesion, transmittance and the like.

INDUSTRIAL APPLICABILITY

The positive photosensitive resin composition excellent in the sensitivity, residual film ratio and storage stability, including a method for forming a cured film using the same, and the positive photosensitive resin composition ensuring that when cured, a cured film excellent in the heat resistance, adhesion, transmittance and the like is obtained, including a method for forming a cured film using the same, which are provided by the present invention, are useful for the formation of a flattening film, a protective film or an interlayer insulating film of electronic components such as liquid crystal display device, integrated circuit device, solid-state imaging device and organic EL.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

This application is based on Japanese Patent Application (Patent Application No. 2007-149217) filed on Jun. 5, 2007, Japanese Patent Application (Patent Application No. 2007-249785) filed on Sep. 26, 2007, and Japanese Patent Application (Patent Application No. 2008-146385) filed on Jun. 4, 2008, the contents of which are incorporated herein by way of reference. 

The invention claimed is:
 1. A positive photosensitive resin composition comprising at least: (A) a resin containing a constituent unit represented by following formula (1) having an acid-dissociable group, and a constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond,

wherein R¹ represents a hydrogen atom, a methyl group, a halogen atom or a cyano group; each of R² and R³ independently represents a hydrogen atom, a linear or branched alkyl group, or a cycloalkyl group, provided that at least one of R² and R³ represents a linear or branched alkyl group or a cycloalkyl group; R⁴ represents a linear or branched alkyl group that may be substituted, a cycloalkyl group that may be substituted, or an aralkyl group that may be substituted; and R² or R³ may combine with R⁴ to form a cyclic ether, wherein the constituent unit having a functional group capable of reacting with a carboxyl group to form a covalent bond is a constituent unit which is formed using a radical polymerizable monomer represented by following formula (3) or (5),

in formulae (3) or (5), X represents a divalent organic group which is —O—, —S—, —COO— or —OCH₂COO—, R⁷ represents a hydrogen atom, a methyl group or a halogen atom, each of R⁸ to R¹⁰ and R¹³ to R¹⁵ independently represents a hydrogen atom or an alkyl group, n is an integer of 1 to 10, the resin being alkali-insoluble or sparingly alkali-soluble and becoming alkali-soluble when the acid-dissociable group dissociates; and (B) a compound capable of generating an acid upon irradiation with an actinic ray or radiation, wherein the component (B) is a compound containing an oxime sulfonate group.
 2. The positive photosensitive resin composition according to claim 1, wherein the component (B) is a compound containing a partial structure represented by formula (2):

wherein R⁵ represents a linear or branched alkyl group that may be substituted, a cycloalkyl group that may be substituted, or an aryl group that may be substituted.
 3. The positive photosensitive resin composition according to claim 1, wherein the component (B) is a compound represented by following formula (3):

wherein R⁵ is the same as R⁵ in formula (2); X represents a linear or branched alkyl group, an alkoxy group or a halogen atom; m represents an integer of 0 to 3; and when m is 2 or 3, each X may be the same as or different from every other X.
 4. The positive photosensitive resin composition according to claim 1, which further comprises: (C) an adhesion aid.
 5. A method for forming a cured film, comprising: a step of coating and drying the positive photosensitive resin composition according to claim 1 on a substrate to form a coating; a step of exposing the coating to an actinic ray or radiation through a mask; a step of developing the exposed coating with an alkali developer to form a pattern; and a step of heat-treating the obtained pattern.
 6. The method for forming a cured film according to claim 5, which further comprises: a step of exposing an entire surface of the obtained pattern after the step of developing the exposed coating with an alkali developer to foam a pattern but before the step of heat-treating the obtained pattern. 